"Could anyone recommend me a decent tree control that can have extra columns
of text data (like how Outlook Express shows the messages), preferably in
C#."

Hi,

Herfried Wagner, MVP, just put up a post in the
microsoft.public.dotnet.framework.windowsforms group with several links to
opensource Tree-ListView controls on CodeProject, and a link to a commercial
3rd. party control. Look for the thread titled "Re: Tree Control with
Columns?"

Right now I am using the Integral UI TreeView control from Lidor Systems (a
treeview only, not integrated with a ListView), but their IU TV product is
so very powerful (and reasonably priced), the company's developer support is
so good, that I am planning to license and use their Integral TreeListView
product which does have the features you require.

http://www.lidorsystems.com/products/IntegralUI/treelistview.aspx

Happy hunting.

best, Bill

Take a look at Infralution's Virtual Tree.   It supports columns and
can be configured using Context Sensitive columns to display different
columns depending on the space available (like Outlook).  Virtual Tree
also provides lightning quick performance with large data sources.
You can get more information and download an evaluation version from
www.infralution.com/virtualtree.html

Regards
Grant

Hi there,

don't have Outlook Express, but you might want something like this:

http://www.codeproject.com/KB/grid/OutlookGrid.aspx

just as Outlook.

Regards.